Investigate the multifunctional adhesins in Cryptococcus

描述(申请人提供)：除了普通人群中的表浅和皮肤感染外，真菌还可以在免疫受损的个人中引起通常致命的全身感染。例如，新生隐球菌对公众健康构成严重威胁，每年导致50多万人死亡。目前的抗真菌药物疗法远远不能令人满意，迫切需要替代疗法或辅助疗法，包括疫苗接种和免疫疗法。因此，鉴定和鉴定影响真菌和寄主之间相互作用的隐球菌因子是非常必要的。隐球菌有两种形态：酵母菌和丝状菌。以前的研究表明，形态类型与隐球菌毒力之间存在关联。申请人的团队最近发现，转录因子Znf2是形态发生和毒力之间的分子纽带。ZnF2决定细胞黏附、丝状化和产孢子。在小鼠模型中，过表达Znf2的隐球菌细胞刺激保护性宿主免疫反应，失去导致致命疾病的能力。其中一个突出的靶点是黏附蛋白(粘附素)Cfl1。Cfl1在酵母向细丝的转变过程中表达上调，它覆盖在菌丝和菌丝产生的侵染性孢子的表面。重要的是，Cfl1在酵母细胞中的过表达显著改变了隐球菌的毒力。因此，Cfl1很可能参与了宿主和病原体之间的相互作用，Cfl1自然地包裹在隐球菌感染性繁殖的表面。令人惊讶的是，Cfl1不仅作为一种黏附蛋白对复杂群落(生物膜)的形成非常重要，而且释放的Cfl1还作为一种信号分子诱导邻近细胞形成复杂的集落并进行细胞分化。这些初步数据导致了一种假设，即分泌型粘附素通过其多功能来调节真菌群落的行为。这一假设将得到检验。 通过追求以下具体目标。(目的1)阐明由释放的Cfl1启动的信号网络。(目的2)鉴定潜在的粘附素，并检测它们在酵母、菌丝和孢子中的表达模式。由于隐球菌孢子与宿主之间的初始相互作用对感染的结局至关重要，因此对隐球菌孢子表面粘附素的表征对于加深我们对隐球菌生物学和发病机制的了解具有重要意义。这项拟议的研究首次证明了粘附素在非移动真核微生物中的信号传递，也首次研究了孢子粘附素在这种病原体中的作用。鉴于微生物粘附素在感染性疾病中的重要性，本研究将为进一步研究粘附素在隐球菌发病机制中的作用以及进一步开发此类分子的临床应用提供垫脚石。

DESCRIPTION (provided by applicant): Besides superficial and cutaneous infections in the general population, fungi can cause often fatal systemic infections in immune-impaired individuals. For instance, Cryptococcus neoformans poses a serious threat to public health and is responsible for the death of more than half a million people each year. The current antifungal drug therapies are far from satisfactory and there is a critical need for alternative or adjunct therapies, including vaccination and immunotherapy. Thus it is imperative to identify and characterize Cryptococcus factors that shape the interactions between the fungus and the host. Cryptococcus can assume two morphotypes: yeast and filament. Previous studies indicate the association between the morphotype and cryptococcal virulence. The applicant's group recently discovered that the transcription factor Znf2 serves as the molecular link between morphogenesis and virulence. Znf2 dictates cell adhesion, filamentation, and sporulation. Cryptococcus cells with Znf2 overexpression stimulate protective host immune responses and lose the ability to cause fatal diseases in mouse models. One of Znf2's prominent targets is the adhesion protein (adhesin) Cfl1. Cfl1 is up-regulated during the yeast-to-filament transition and it coats the surface of hyphae and infectious spores generated from hyphae. Importantly, overexpression of Cfl1 in the yeast cells significantly alters Cryptococcus virulence. Thus Cfl1, which naturally coats the surface of Cryptococcus infectious propagules, is likely involved in the interaction between the host and the pathogen. Surprisingly, Cfl1 not only is important for the formation of complex communities (biofilm) as an adhesion protein, but the released Cfl1 also elicits neighboring cells to form complex colonies and to undergo cellular differentiation as a signaling molecule. These preliminary data lead to the hypothesis that secreted adhesins regulate fungal community behaviors via their multi-functionalities. This hypothesis will be tested by pursuing the following specific aims. (Aim 1) Elucidate the signaling network initiated by released Cfl1. (Aim 2) Characterize a compendium of potential adhesins and examine their expression pattern in yeasts, hyphae and spores. Because the initial interaction between Cryptococcus spores and the host is critical for the outcome of the infection, characterization of adhesins on the surface of Cryptococcus spores is important for advancing our understanding of Cryptococcus biology and pathogenesis. This proposed research is the first to demonstrate adhesin-mediated signaling in a non-mobile eukaryotic microbe, and the first to investigate spore adhesins in this pathogen. Given the importance of microbial adhesins in infectious diseases, this research will provide a stepping stone for further investigation of adhesins' roles in Cryptococcus pathogenesis and for future exploitation of such molecules for clinical applications.